/* ========================================
   河北梦朗建设工程有限公司 - 官网样式 V2
   ======================================== */

/* CSS Variables */
:root {
  --primary: #1565c0;
  --primary-dark: #0d47a1;
  --primary-light: #1976d2;
  --accent: #ff6f00;
  --accent-light: #ff8f00;
  --dark: #1a1a2e;
  --gray-dark: #333;
  --gray: #666;
  --gray-light: #999;
  --gray-lighter: #e8e8e8;
  --white: #fff;
  --bg-light: #f5f7fa;
  --bg-gray: #f0f2f5;
  --shadow: 0 4px 20px rgba(0, 0, 0, 0.08);
  --shadow-lg: 0 10px 40px rgba(0, 0, 0, 0.12);
  --transition: all 0.3s ease;
}

/* Reset & Base */
*, *::before, *::after {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
  font-size: 16px;
}

body {
  font-family: 'Noto Sans SC', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  color: var(--gray-dark);
  line-height: 1.6;
  background: var(--white);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

a {
  text-decoration: none;
  color: inherit;
  transition: var(--transition);
}

ul {
  list-style: none;
}

img {
  max-width: 100%;
  height: auto;
  display: block;
}

button {
  border: none;
  background: none;
  cursor: pointer;
  font-family: inherit;
}

/* Container */
.container {
  width: 100%;
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 24px;
}

/* ========================================
   Header - 导航栏
   ======================================== */
.header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 1000;
  background: var(--white);
  box-shadow: var(--shadow);
  transition: var(--transition);
}

.header.scrolled {
  background: rgba(255, 255, 255, 0.98);
  backdrop-filter: blur(10px);
}

.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 80px;
}

/* Logo */
.logo {
  display: flex;
  align-items: center;
  gap: 14px;
}

.logo-img {
  height: 48px;
  width: auto;
}

.logo-icon {
  width: 48px;
  height: 48px;
  background: linear-gradient(135deg, var(--primary) 0%, var(--primary-light) 100%);
  border-radius: 8px;
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--white);
}

.logo-letter {
  font-size: 26px;
  font-weight: 700;
}

.logo-text-group {
  display: flex;
  flex-direction: column;
}

.logo-text {
  font-size: 18px;
  font-weight: 700;
  color: var(--primary-dark);
  letter-spacing: 1px;
}

.logo-sub {
  font-size: 10px;
  color: var(--gray);
  letter-spacing: 2px;
}

/* Header Phone */
.header-phone {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 8px 16px;
  background: var(--bg-light);
  border-radius: 50px;
  color: var(--primary);
  font-size: 14px;
  font-weight: 500;
}

.header-phone svg {
  width: 18px;
  height: 18px;
}

/* Navigation */
.nav {
  display: flex;
}

.nav-list {
  display: flex;
  gap: 36px;
}

.nav-link {
  position: relative;
  font-size: 15px;
  font-weight: 500;
  color: var(--gray-dark);
  padding: 8px 0;
}

.nav-link::after {
  content: '';
  position: absolute;
  bottom: 0;
  left: 0;
  width: 0;
  height: 2px;
  background: var(--primary);
  transition: var(--transition);
}

.nav-link:hover::after,
.nav-link.active::after {
  width: 100%;
}

.nav-link:hover,
.nav-link.active {
  color: var(--primary);
}

/* Menu Toggle (Mobile) */
.menu-toggle {
  display: none;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  width: 44px;
  height: 44px;
  gap: 5px;
}

.menu-toggle span {
  display: block;
  width: 24px;
  height: 2px;
  background: var(--gray-dark);
  transition: var(--transition);
}

.menu-toggle.active span:nth-child(1) {
  transform: rotate(45deg) translate(5px, 5px);
}

.menu-toggle.active span:nth-child(2) {
  opacity: 0;
}

.menu-toggle.active span:nth-child(3) {
  transform: rotate(-45deg) translate(5px, -5px);
}

/* Menu Overlay */
.menu-overlay {
  display: none;
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background: rgba(0, 0, 0, 0.5);
  z-index: 998;
  opacity: 0;
  transition: opacity 0.3s;
}

.menu-overlay.active {
  display: block;
  opacity: 1;
}

/* ========================================
   Hero Section - 首屏
   ======================================== */
.hero {
  position: relative;
  min-height: 100vh;
  display: flex;
  align-items: center;
  overflow: hidden;
  padding-top: 80px;
}

.hero-bg {
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background: url('../assets/images/case-1.jpg') center/cover no-repeat;
}

.hero-overlay {
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background: linear-gradient(135deg, rgba(13, 71, 161, 0.92) 0%, rgba(21, 101, 192, 0.88) 100%);
}

/* Particles */
.hero-particles {
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  overflow: hidden;
}

.hero-content {
  position: relative;
  z-index: 2;
  padding: 80px 0;
  display: flex;
  flex-direction: column;
  align-items: flex-start;
  max-width: 800px;
}

.hero-text {
  color: var(--white);
}

.hero-badge {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 8px 16px;
  background: rgba(255, 255, 255, 0.15);
  border-radius: 50px;
  font-size: 14px;
  margin-bottom: 24px;
  backdrop-filter: blur(10px);
}

.badge-icon {
  display: flex;
}

.badge-icon svg {
  width: 16px;
  height: 16px;
}

.hero-title {
  font-size: 52px;
  font-weight: 700;
  line-height: 1.15;
  margin-bottom: 12px;
  letter-spacing: 2px;
}

.hero-subtitle {
  font-size: 18px;
  font-weight: 400;
  margin-bottom: 24px;
  opacity: 0.85;
  letter-spacing: 4px;
}

.hero-desc {
  font-size: 18px;
  line-height: 1.9;
  margin-bottom: 40px;
  opacity: 0.9;
}

/* Hero Feature */
.hero-feature {
  display: flex;
  gap: 40px;
  margin-top: 60px;
  padding-top: 40px;
  border-top: 1px solid rgba(255, 255, 255, 0.2);
}

.feature-item {
  text-align: center;
  color: var(--white);
}

.feature-num {
  font-size: 36px;
  font-weight: 700;
  line-height: 1;
}

.feature-unit {
  font-size: 20px;
  font-weight: 500;
}

.feature-label {
  display: block;
  font-size: 13px;
  opacity: 0.8;
  margin-top: 8px;
}

/* Buttons */
.hero-btns {
  display: flex;
  gap: 16px;
  flex-wrap: wrap;
}

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 14px 36px;
  font-size: 15px;
  font-weight: 500;
  border-radius: 4px;
  transition: var(--transition);
  letter-spacing: 1px;
}

.btn-primary {
  background: var(--accent);
  color: var(--white);
}

.btn-primary:hover {
  background: var(--accent-light);
  transform: translateY(-2px);
  box-shadow: 0 10px 30px rgba(255, 111, 0, 0.35);
}

.btn-outline {
  border: 2px solid var(--white);
  color: var(--white);
  background: transparent;
}

.btn-outline:hover {
  background: var(--white);
  color: var(--primary-dark);
}

/* Hero Scroll */
.hero-scroll {
  position: absolute;
  bottom: 40px;
  left: 50%;
  transform: translateX(-50%);
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 10px;
  color: var(--white);
  opacity: 0.7;
  animation: bounce 2s infinite;
}

.hero-scroll span {
  font-size: 12px;
  letter-spacing: 2px;
}

.scroll-arrow {
  width: 20px;
  height: 20px;
  border-right: 2px solid currentColor;
  border-bottom: 2px solid currentColor;
  transform: rotate(45deg);
}

@keyframes bounce {
  0%, 20%, 50%, 80%, 100% { transform: translateX(-50%) translateY(0); }
  40% { transform: translateX(-50%) translateY(-10px); }
  60% { transform: translateX(-50%) translateY(-5px); }
}

/* ========================================
   Advantage Section - 服务优势
   ======================================== */
.advantage-section {
  padding: 40px 0;
  background: var(--white);
  margin-top: -60px;
  position: relative;
  z-index: 10;
}

.advantage-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 24px;
  background: var(--white);
  border-radius: 16px;
  padding: 40px;
  box-shadow: var(--shadow-lg);
}

.advantage-item {
  display: flex;
  align-items: flex-start;
  gap: 16px;
  padding: 20px;
  border-radius: 12px;
  transition: var(--transition);
}

.advantage-item:hover {
  background: var(--bg-light);
}

.advantage-icon {
  flex-shrink: 0;
  width: 52px;
  height: 52px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: linear-gradient(135deg, var(--primary) 0%, var(--primary-light) 100%);
  border-radius: 12px;
  color: var(--white);
}

.advantage-icon svg {
  width: 26px;
  height: 26px;
}

.advantage-text h4 {
  font-size: 16px;
  font-weight: 600;
  color: var(--dark);
  margin-bottom: 4px;
}

.advantage-text p {
  font-size: 13px;
  color: var(--gray);
  line-height: 1.5;
}

/* ========================================
   Sections - 通用样式
   ======================================== */
.section {
  padding: 100px 0;
}

.section-header {
  text-align: center;
  margin-bottom: 60px;
}

.section-tag {
  display: inline-block;
  font-size: 13px;
  font-weight: 500;
  color: var(--accent);
  letter-spacing: 3px;
  margin-bottom: 12px;
  position: relative;
}

.section-tag::before,
.section-tag::after {
  content: '';
  position: absolute;
  top: 50%;
  width: 40px;
  height: 1px;
  background: var(--gray-lighter);
}

.section-tag::before {
  right: calc(100% + 16px);
}

.section-tag::after {
  left: calc(100% + 16px);
}

.section-title {
  font-size: 36px;
  font-weight: 700;
  color: var(--dark);
  margin-bottom: 16px;
}

.section-desc {
  font-size: 16px;
  color: var(--gray);
}

/* ========================================
   About Section - 关于我们
   ======================================== */
.about-section {
  background: var(--bg-light);
}

.about-content {
  display: grid;
  grid-template-columns: 1fr 1.2fr;
  gap: 60px;
  align-items: center;
}

.about-images {
  position: relative;
}

.about-img-main {
  border-radius: 16px;
  overflow: hidden;
  box-shadow: var(--shadow-lg);
}

.about-img-main img {
  width: 100%;
  height: 360px;
  object-fit: cover;
}

.about-img-secondary {
  position: absolute;
  bottom: -40px;
  right: -30px;
  width: 200px;
  border-radius: 12px;
  overflow: hidden;
  box-shadow: var(--shadow-lg);
}

.about-img-secondary img {
  width: 100%;
  height: 140px;
  object-fit: cover;
}

.about-year {
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background: linear-gradient(135deg, var(--primary) 0%, var(--primary-light) 100%);
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  color: var(--white);
}

.year-num {
  font-size: 32px;
  font-weight: 700;
}

.year-text {
  font-size: 12px;
  opacity: 0.9;
}

.about-badge {
  display: inline-flex;
  flex-direction: column;
  align-items: flex-start;
  padding: 8px 16px;
  background: linear-gradient(135deg, var(--accent) 0%, var(--accent-light) 100%);
  border-radius: 8px;
  margin-bottom: 20px;
}

.badge-text {
  font-size: 14px;
  font-weight: 600;
  color: var(--white);
}

.badge-sub {
  font-size: 11px;
  color: rgba(255, 255, 255, 0.85);
}

.about-info h3 {
  font-size: 28px;
  font-weight: 700;
  color: var(--dark);
  margin-bottom: 20px;
}

.about-info p {
  font-size: 15px;
  line-height: 1.9;
  color: var(--gray);
  margin-bottom: 16px;
}

.about-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  margin-top: 24px;
}

.tag {
  padding: 8px 16px;
  background: var(--white);
  border: 1px solid var(--gray-lighter);
  border-radius: 50px;
  font-size: 13px;
  color: var(--gray-dark);
  transition: var(--transition);
}

.tag:hover {
  border-color: var(--primary);
  color: var(--primary);
}

/* ========================================
   Services Section - 业务范围
   ======================================== */
.services-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 30px;
}

.service-card {
  position: relative;
  padding: 40px 30px;
  background: var(--white);
  border-radius: 16px;
  box-shadow: var(--shadow);
  text-align: center;
  transition: var(--transition);
  border: 1px solid transparent;
  overflow: hidden;
}

.service-card::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 4px;
  background: linear-gradient(90deg, var(--primary), var(--primary-light));
  transform: scaleX(0);
  transition: var(--transition);
}

.service-card:hover {
  transform: translateY(-8px);
  box-shadow: var(--shadow-lg);
  border-color: var(--primary);
}

.service-card:hover::before {
  transform: scaleX(1);
}

.service-icon {
  width: 80px;
  height: 80px;
  margin: 0 auto 24px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: linear-gradient(135deg, rgba(21, 101, 192, 0.1) 0%, rgba(25, 118, 210, 0.1) 100%);
  border-radius: 50%;
  color: var(--primary);
  transition: var(--transition);
}

.service-card:hover .service-icon {
  background: linear-gradient(135deg, var(--primary) 0%, var(--primary-light) 100%);
  color: var(--white);
}

.service-icon svg {
  width: 40px;
  height: 40px;
}

.service-title {
  font-size: 20px;
  font-weight: 600;
  color: var(--dark);
  margin-bottom: 12px;
}

.service-desc {
  font-size: 14px;
  line-height: 1.7;
  color: var(--gray);
}

.service-brand {
  display: inline-block;
  margin-top: 16px;
  padding: 4px 12px;
  background: linear-gradient(135deg, var(--accent) 0%, var(--accent-light) 100%);
  color: var(--white);
  font-size: 12px;
  font-weight: 500;
  border-radius: 50px;
}

/* ========================================
   Cases Section - 工程案例
   ======================================== */
.cases-section {
  background: var(--bg-gray);
}

.cases-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 30px;
}

.case-card {
  position: relative;
  border-radius: 16px;
  overflow: hidden;
  box-shadow: var(--shadow);
  background: var(--white);
}

.case-card.case-large {
  grid-column: span 2;
  grid-row: span 2;
}

.case-img {
  position: relative;
  overflow: hidden;
}

.case-card:not(.case-large) .case-img {
  height: 220px;
}

.case-large .case-img {
  height: 100%;
  min-height: 480px;
}

.case-img img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  transition: transform 0.6s ease;
}

.case-card:hover .case-img img {
  transform: scale(1.08);
}

.case-info {
  padding: 24px;
}

.case-tag {
  display: inline-block;
  padding: 4px 12px;
  font-size: 12px;
  font-weight: 500;
  color: var(--accent);
  background: rgba(255, 111, 0, 0.1);
  border-radius: 50px;
  margin-bottom: 12px;
}

.case-title {
  font-size: 18px;
  font-weight: 600;
  color: var(--dark);
  margin-bottom: 8px;
}

.case-desc {
  font-size: 14px;
  color: var(--gray);
  line-height: 1.6;
}

/* ========================================
   Honor Section - 资质荣誉
   ======================================== */
.honor-content {
  background: var(--white);
  border-radius: 20px;
  padding: 60px;
  box-shadow: var(--shadow);
}

.honor-list {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 30px;
}

.honor-item {
  display: flex;
  align-items: flex-start;
  gap: 16px;
  padding: 24px;
  border-radius: 12px;
  transition: var(--transition);
  border: 1px solid var(--gray-lighter);
}

.honor-item:hover {
  border-color: var(--primary);
  background: rgba(21, 101, 192, 0.03);
}

.honor-icon {
  flex-shrink: 0;
  width: 56px;
  height: 56px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: linear-gradient(135deg, var(--primary) 0%, var(--primary-light) 100%);
  border-radius: 12px;
  color: var(--white);
}

.honor-icon svg {
  width: 28px;
  height: 28px;
}

.honor-text h4 {
  font-size: 15px;
  font-weight: 600;
  color: var(--dark);
  margin-bottom: 6px;
}

.honor-text p {
  font-size: 13px;
  color: var(--gray);
  line-height: 1.5;
}

/* ========================================
   Brand Section - 品牌展示
   ======================================== */
.brand-section {
  padding: 100px 0;
  background: linear-gradient(135deg, var(--dark) 0%, #2a2a4a 100%);
  color: var(--white);
}

.brand-section .section-header {
  margin-bottom: 40px;
}

.brand-section .section-tag {
  color: var(--accent);
}

.brand-section .section-tag::before,
.brand-section .section-tag::after {
  background: rgba(255, 255, 255, 0.2);
}

.brand-section .section-title {
  color: var(--white);
}

.brand-section .section-desc {
  color: rgba(255, 255, 255, 0.7);
}

.brand-content {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 60px;
  align-items: center;
}

.brand-showcase {
  display: flex;
  flex-direction: column;
  gap: 30px;
}

.brand-logo {
  display: flex;
  align-items: center;
  gap: 20px;
}

.brand-logo-img {
  height: 70px;
  width: auto;
}

.brand-logo .brand-letter {
  width: 80px;
  height: 80px;
  background: linear-gradient(135deg, var(--accent) 0%, var(--accent-light) 100%);
  border-radius: 16px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 40px;
  font-weight: 700;
}

.brand-logo .brand-name {
  font-size: 32px;
  font-weight: 700;
  color: var(--white);
}

.brand-desc p {
  font-size: 15px;
  line-height: 1.9;
  color: rgba(255, 255, 255, 0.8);
  margin-bottom: 16px;
}

.brand-products {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 20px;
}

.product-item {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 12px;
  padding: 30px 20px;
  background: rgba(255, 255, 255, 0.08);
  border-radius: 16px;
  transition: var(--transition);
  border: 1px solid rgba(255, 255, 255, 0.1);
}

.product-item:hover {
  background: rgba(255, 255, 255, 0.15);
  transform: translateY(-4px);
}

.product-icon {
  width: 60px;
  height: 60px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: rgba(255, 111, 0, 0.2);
  border-radius: 12px;
  color: var(--accent);
}

.product-icon svg {
  width: 32px;
  height: 32px;
}

.product-item span {
  font-size: 14px;
  font-weight: 500;
}

/* ========================================
   Contact Section - 联系我们
   ======================================== */
.contact-section {
  background: var(--bg-light);
}

.contact-content {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 60px;
}

.contact-info {
  display: flex;
  flex-direction: column;
  gap: 20px;
}

.contact-item {
  display: flex;
  align-items: flex-start;
  gap: 16px;
  padding: 24px;
  background: var(--white);
  border-radius: 12px;
  box-shadow: var(--shadow);
  transition: var(--transition);
}

.contact-item:hover {
  transform: translateX(8px);
  box-shadow: var(--shadow-lg);
}

.contact-icon {
  flex-shrink: 0;
  width: 48px;
  height: 48px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: linear-gradient(135deg, var(--primary) 0%, var(--primary-light) 100%);
  border-radius: 10px;
  color: var(--white);
}

.contact-icon svg {
  width: 22px;
  height: 22px;
}

.contact-text {
  display: flex;
  flex-direction: column;
  gap: 4px;
}

.contact-label {
  font-size: 13px;
  color: var(--gray);
}

.contact-value {
  font-size: 15px;
  font-weight: 500;
  color: var(--dark);
}

/* Map */
.contact-map {
  display: flex;
  align-items: center;
  justify-content: center;
}

.map-wrapper {
  width: 100%;
  height: 100%;
  min-height: 450px;
}

.map-info {
  width: 100%;
  height: 100%;
  background: linear-gradient(135deg, var(--primary) 0%, var(--primary-dark) 100%);
  border-radius: 20px;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  color: var(--white);
  text-align: center;
  padding: 40px;
}

.map-icon {
  width: 100px;
  height: 100px;
  margin-bottom: 24px;
  opacity: 0.9;
}

.map-icon svg {
  width: 100%;
  height: 100%;
}

.map-info h4 {
  font-size: 24px;
  font-weight: 600;
  margin-bottom: 12px;
}

.map-info p {
  font-size: 16px;
  opacity: 0.9;
  margin-bottom: 8px;
}

.map-info span {
  font-size: 14px;
  opacity: 0.7;
}

/* ========================================
   Footer - 页脚
   ======================================== */
.footer {
  background: var(--dark);
  color: var(--white);
  padding: 80px 0 0;
}

.footer-content {
  display: flex;
  justify-content: space-between;
  padding-bottom: 50px;
  border-bottom: 1px solid rgba(255, 255, 255, 0.1);
}

.footer-brand {
  max-width: 320px;
}

.footer-logo {
  display: flex;
  align-items: center;
  gap: 14px;
  margin-bottom: 20px;
}

.footer-logo-img {
  height: 50px;
  width: auto;
}

.footer-logo .logo-letter {
  width: 50px;
  height: 50px;
  background: linear-gradient(135deg, var(--primary) 0%, var(--primary-light) 100%);
  border-radius: 10px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 28px;
  font-weight: 700;
}

.footer-logo .logo-text-group {
  display: flex;
  flex-direction: column;
}

.footer-logo .logo-name {
  font-size: 20px;
  font-weight: 700;
  color: var(--white);
}

.footer-logo .logo-sub {
  font-size: 11px;
  opacity: 0.6;
  letter-spacing: 2px;
  color: rgba(255, 255, 255, 0.6);
}

.footer-brand p {
  font-size: 14px;
  opacity: 0.7;
  line-height: 1.6;
}

.footer-links {
  display: flex;
  gap: 80px;
}

.footer-col h4 {
  font-size: 16px;
  font-weight: 600;
  margin-bottom: 24px;
}

.footer-col ul {
  display: flex;
  flex-direction: column;
  gap: 12px;
}

.footer-col a {
  font-size: 14px;
  opacity: 0.7;
  transition: var(--transition);
}

.footer-col a:hover {
  opacity: 1;
  color: var(--accent);
}

.footer-bottom {
  padding: 24px 0;
  text-align: center;
}

.footer-info {
  display: flex;
  justify-content: center;
  gap: 16px;
  font-size: 13px;
  opacity: 0.6;
  margin-bottom: 12px;
}

.footer-bottom p {
  font-size: 13px;
  opacity: 0.5;
}

/* ========================================
   Back to Top
   ======================================== */
.back-top {
  position: fixed;
  bottom: 30px;
  right: 30px;
  width: 50px;
  height: 50px;
  background: var(--primary);
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--white);
  box-shadow: var(--shadow);
  opacity: 0;
  visibility: hidden;
  transition: var(--transition);
  z-index: 999;
}

.back-top.visible {
  opacity: 1;
  visibility: visible;
}

.back-top:hover {
  background: var(--accent);
  transform: translateY(-3px);
}

.back-top svg {
  width: 24px;
  height: 24px;
}

/* ========================================
   Responsive - 响应式设计
   ======================================== */

/* Tablet */
@media (max-width: 1024px) {
  .hero-title {
    font-size: 40px;
  }
  
  .hero-feature {
    gap: 30px;
  }
  
  .feature-num {
    font-size: 30px;
  }
  
  .advantage-grid {
    grid-template-columns: repeat(2, 1fr);
  }
  
  .about-content {
    grid-template-columns: 1fr;
    gap: 40px;
  }
  
  .about-images {
    max-width: 500px;
    margin: 0 auto;
  }
  
  .services-grid {
    grid-template-columns: repeat(2, 1fr);
  }
  
  .cases-grid {
    grid-template-columns: repeat(2, 1fr);
  }
  
  .case-card.case-large {
    grid-column: span 2;
    grid-row: span 1;
  }
  
  .case-large .case-img {
    min-height: 300px;
  }
  
  .honor-list {
    grid-template-columns: repeat(2, 1fr);
    gap: 20px;
  }
  
  .honor-content {
    padding: 40px;
  }
  
  .brand-content {
    grid-template-columns: 1fr;
    gap: 40px;
  }
  
  .contact-content {
    grid-template-columns: 1fr;
  }
  
  .header-phone {
    display: none;
  }
}

/* Mobile */
@media (max-width: 768px) {
  .header-inner {
    height: 70px;
  }
  .hero-text {
    width: 90%;
    margin: 0 auto;
  }
  .logo-text-group {
    display: none;
  }
  
  .nav {
    position: fixed;
    top: 0;
    right: -300px;
    width: 300px;
    height: 100vh;
    background: var(--white);
    padding: 100px 30px 30px;
    box-shadow: var(--shadow-lg);
    transition: right 0.3s ease;
    z-index: 999;
  }
  
  .nav.active {
    right: 0;
  }
  
  .nav-list {
    flex-direction: column;
    gap: 0;
  }
  
  .nav-link {
    display: block;
    padding: 16px 0;
    font-size: 16px;
    border-bottom: 1px solid var(--gray-lighter);
  }
  
  .menu-toggle {
    display: flex;
    z-index: 1000;
  }
  
  .hero {
    min-height: auto;
    padding: 120px 0 80px;
  }
  
  .hero-title {
    font-size: 28px;
  }
  
  .hero-subtitle {
    font-size: 14px;
    letter-spacing: 2px;
  }
  
  .hero-desc {
    font-size: 15px;
  }
  
  .hero-btns {
    flex-direction: column;
    width: 100%;
  }
  
  .btn {
    width: 100%;
  }
  
  .hero-feature {
    flex-direction: column;
    gap: 20px;
    width: 100%;
    padding-top: 30px;
  }
  
  .feature-item {
    display: flex;
    align-items: center;
    gap: 12px;
    text-align: left;
    padding: 16px;
    background: rgba(255, 255, 255, 0.1);
    border-radius: 12px;
  }
  
  .feature-num {
    font-size: 28px;
  }
  
  .hero-scroll {
    display: none;
  }
  
  .advantage-section {
    padding: 20px 0;
    margin-top: 0;
  }
  
  .advantage-grid {
    grid-template-columns: 1fr;
    padding: 24px;
    gap: 16px;
  }
  
  .advantage-item {
    padding: 16px;
  }
  
  .section {
    padding: 60px 0;
  }
  
  .section-title {
    font-size: 28px;
  }
  
  .section-tag::before,
  .section-tag::after {
    width: 24px;
  }
  
  .about-img-secondary {
    position: relative;
    bottom: auto;
    right: auto;
    width: 100%;
    margin-top: 20px;
  }
  
  .about-info h3 {
    font-size: 22px;
  }
  
  .services-grid {
    grid-template-columns: 1fr;
  }
  
  .cases-grid {
    grid-template-columns: 1fr;
  }
  
  .case-card.case-large {
    grid-column: span 1;
  }
  
  .case-large .case-img {
    min-height: 220px;
  }
  
  .honor-content {
    padding: 24px;
  }
  
  .honor-list {
    grid-template-columns: 1fr;
    gap: 16px;
  }
  
  .honor-item {
    padding: 16px;
  }
  
  .brand-products {
    grid-template-columns: 1fr 1fr;
    gap: 12px;
  }
  
  .product-item {
    padding: 20px 16px;
  }
  
  .product-icon {
    width: 48px;
    height: 48px;
  }
  
  .product-icon svg {
    width: 24px;
    height: 24px;
  }
  
  .footer-content {
    flex-direction: column;
    gap: 40px;
    text-align: center;
  }
  
  .footer-links {
    flex-direction: column;
    gap: 30px;
    width: 100%;
  }
  
  .footer-col {
    text-align: center;
  }
  
  .footer-col ul {
    align-items: center;
  }
  
  .back-top {
    bottom: 20px;
    right: 20px;
    width: 44px;
    height: 44px;
  }
}

/* Small Mobile */
@media (max-width: 480px) {
  .container {
    padding: 0 16px;
  }
  
  .hero-title {
    font-size: 24px;
  }
  
  .hero-text {
    margin: 0 auto;
  }
  
  .section-title {
    font-size: 24px;
  }
  
  .advantage-icon {
    width: 44px;
    height: 44px;
  }
  
  .advantage-icon svg {
    width: 22px;
    height: 22px;
  }
  
  .service-icon {
    width: 64px;
    height: 64px;
  }
  
  .service-icon svg {
    width: 32px;
    height: 32px;
  }
  
  .brand-logo-img {
    height: 50px;
  }

  .brand-logo .brand-letter {
    width: 60px;
    height: 60px;
    font-size: 30px;
  }
  
  .brand-logo .brand-name {
    font-size: 24px;
  }
}